Major winter storm incoming for Ontario/Quebec


15z surface analysis by the National Weather Service

A major Colorado Low is forming in the High Plains of the United States on the lee side of the Colorado Rockies this morning. The Low is expected to track southeast then northeast as the upper-level trough becomes more negatively-tilted and its associated surface Low pressure deepens. The deepening of the Low is showing a significant winter storm and possibly blizzard conditions will be possible for southern Ontario and Quebec on Tuesday and Wednesday.

What to expect:

  • Significant disruption of Tuesday evening commute

  • Significant disruption of Wednesday morning/evening commute

  • Blizzard conditions in opened areas

  • Significant drifting of snow and reduced visibility on Wednesday

  • Significant accumulations in GTA area, Capital Region and major cities in Quebec

  • Freezing rain/sleet/heavy snow for southwestern Ontario

NAM 3km model showing precipitation type and Low deepening on Tuesday/Wednesday

Above is a depiction of the Low deepening on Tuesday night. A first axis of precipitation is expected to bring mixed precipitation such as freezing rain, sleet and heavy snow on Tuesday for S Ontario/Quebec. However, more snow is expected as the Low approaches S Ontario on Tuesday night into early Wednesday. This will bring all snow to S Ontario/Quebec and possibly blizzard conditions in opened-areas.

Low position on Wednesday morning showing deep Low around 989mb

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Forecasted snowfall accumulations by the NAM 12km model over a 24hrs (using 10:1 ratio)
  • City of Toronto: 20-25cm possible

  • Hamilton: 25-30cm possible

  • Peterborough area: 30-35cm possible

  • Ottawa-Gatineau area: 40-45cm possible

  • Montreal: 35-45cm possible

Blizzard conditions on Wednesday



Watches

10:51 AM EST Monday 11 February 2019 Winter storm watch in effect for:

  • City of Toronto

Winter storm with a combination of 15 to 20 cm snow and ice pellets, possible freezing rain, and strong winds expected Tuesday and Tuesday night. Snow will begin early Tuesday morning. Snow will mix with or change to ice pellets later Tuesday. Strong easterly winds gusting to 80 km/h will cause reduced visibility in blowing snow. Total snowfall and ice pellet amounts of 15 to 25 cm are possible before ending Wednesday. There is also a risk of freezing rain. Localized power outages possible. This weather is associated with a Colorado low that will cross Southern Ontario Tuesday and Wednesday. Rapidly accumulating snow could make travel difficult over some locations. Visibility may be suddenly reduced at times in heavy snow. Surfaces such as highways, roads, walkways and parking lots may become icy and slippery. Poor weather conditions may contribute to transportation delays. There may be a significant impact on rush hour traffic in urban areas.